Cooling system for built-in microwave oven

Abstract

A built-in microwave oven is provided, installed in the kitchen furniture as an integral part of the furniture. In the microwave oven, a suction grille and an exhaust grille are provided on the front wall of the external casing, and so cooling air is sucked and discharged through the front wall of the casing. Upper and lower heaters are installed within the casing, with an upper inside air passage formed around the upper heater that guide an air current formed by an upper heater cooling fan, and another air passage is formed around the lower heater that guides an air current formed by a lower heater cooling fan. The inflow air from the suction grille is partially and directly guided to the exhaust grille so as to be mixed with hot air from the upper and lower heaters prior to being discharged from the external casing to the atmosphere through the exhaust grille. Therefore, the exhaust air from the exhaust grille is preferably reduced in its temperature to a proper low point.

What is claimed is:  
     
       1. A built-in microwave oven, comprising: 
       a suction grille provided on an upper portion of a front wall of an external casing of said microwave oven for sucking air into the external casing;  
       an exhaust grille provided on a lower portion of said front wall of the external casing for discharging air from the external casing to the atmosphere; and  
       means for forming air currents within the external casing while guiding inflow air from the suction grille to allow the inflow air to pass within the external casing prior to discharging the air from the external casing to the atmosphere through the exhaust grille; and  
       means for cooling the air prior to discharging the air to the atmosphere.  
     
     
       2. A built-in microwave oven, comprising: 
       a suction grille provided on a front wall of an external casing of said microwave oven at a predetermined position for inflowing atmospheric air into the external casing;  
       an exhaust grille provided on said front wall of the external casing at another predetermined position for discharging air from the external casing to the atmosphere;  
       at least one heating means used for heating food seated within a cooking cavity of the oven;  
       a first air passage guiding a part of inflow atmospheric air from the suction grille to the exhaust grille;  
       a second air passage guiding a remaining part of the inflow atmospheric air from the suction grille to the exhaust grille while allowing the air to pass by said heating means to cool the heating means; and  
       means for forming air currents within the external casing by sucking the inflow atmospheric air through the suction grille and by allowing the inflow atmospheric air to pass through both the first and second air passages prior to discharging the air from the external casing to the atmosphere through the exhaust grille,  
       whereby said first air passage is configured to cool the air of the second air passage at a position before the exhaust grille.  
     
     
       3. The built-in microwave oven according to  claim 2 , wherein said suction grille is provided on the front wall of said external casing at a predetermined upper position, and said exhaust grille is provided on the front wall of said external casing at a predetermined lower position. 
     
     
       4. The built-in microwave oven according to  claim 3 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between a top wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing;  
       wherein said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       5. The built-in microwave oven according to  claim 3 , wherein said heating means comprises an upper heater externally provided on a top wall of said cavity, and a lower heater externally provided on a bottom of said cavity, with a lower heater cooling air passage formed around the lower heater to allow an air current to flow through while cooling said lower heater, and fourth air current forming means for forming the air current flowing in said lower heater cooling air passage, whereby the air current from said lower heater cooling air passage is discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       6. The built-in microwave oven according to  claim 2 , further comprising a channel member used for forming an air duct and guiding an air current to flow through the air duct so as to prevent heat of said heating means from being transferred to said external casing. 
     
     
       7. The built-in microwave oven according to  claim 6 , further comprising a reflection plate installed within said channel member for reflecting heat from said heating means into said cavity. 
     
     
       8. The built-in microwave oven of  claim 2 , comprising at least one partition panel separating the first air passage and the second air passage, respectively. 
     
     
       9. A built-in microwave oven, comprising: 
       an external casing forming a profile of said microwave oven;  
       a cooking cavity set within the external casing and used for heating food seated therein;  
       a partition panel unit used for dividing a channel between said external casing and said cooking cavity into inside and outside passages;  
       heating means installed within said inside passage between the partition panel unit and a top wall of the cavity and used for generating heat and radiating the heat into said cooking cavity;  
       a suction grille and an exhaust grille provided on a front wall of said external casing at predetermined upper and lower positions, respectively;  
       first air current forming means for guiding inflow air from the suction grille to allow said air to pass through said inside passage between the partition panel unit and a top wall of the cavity while cooling the heating means prior to discharging the air from the external casing to the atmosphere through the exhaust grille; and  
       second air current forming means for guiding the inflow air from the suction grille to allow said air to pass through said outside passage between the partition panel unit and a top wall of said external casing prior to reaching the exhaust grille;  
       whereby an air current formed by the first air current forming means is mixed with another air current formed by the second air current forming means prior to being discharged from the external casing to the atmosphere through the exhaust grille.  
     
     
       10. The built-in microwave oven according to  claim 9 , further comprising 
       a machine chamber provided within said external casing at a position around the cooking cavity, and encasing high-frequency electromagnetic wave generating means therein; and  
       third air current forming means for partially guiding the inflow air from the suction grille to allow said air to pass through the machine chamber prior to reaching the exhaust grille.  
     
     
       11. The built-in microwave oven according to  claim 10 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between a top wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing;  
       wherein said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       12. The built-in microwave oven according to  claim 10 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between a top wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing;  
       wherein said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       13. The built-in microwave oven according to  claim 10 , wherein said heating means comprises an upper heater externally provided on a top wall of said cavity, and a lower heater externally provided on a bottom of said cavity, with a lower heater cooling air passage formed around the lower heater to allow an air current to flow through while cooling said lower heater, and fourth air current forming means for forming the air current flowing in said lower heater cooling air passage, whereby the air current from said lower heater cooling air passage is discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       14. The built-in microwave oven according to  claim 10 , further comprising a partition wall installed at a junction of the bottom wall of said cavity and the bottom wall of said machine chamber and used for preventing exhaust air from being undesirably introduced into said machine chamber prior to being discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       15. The built-in microwave oven according to  claim 9 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between a top wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing,  
       whereby said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       16. The built-in microwave oven according to  claim 15 , further comprising a central guide provided within the external casing at a position before the exhaust grille for guiding a mixed air current, formed by a mixing of the air currents from the inside and outside passages defined under the bottom wall of said cavity by said lower partition panel, to opposite end portions of the exhaust grille. 
     
     
       17. The built-in microwave oven according to  claim 16 , further comprising a sub-guide provided at a position under the lower partition panel and used for secondarily dividing an air current, flowing from the outside passage defined outside the sidewall of said cavity and guided along a sidewall of said central guide toward an end portion of said exhaust grille, into two air currents. 
     
     
       18. The built-in microwave oven according to  claim 9 , wherein said heating means comprises an upper heater externally provided on a top wall of said cavity, and a lower heater externally provided on a bottom wall of said cavity, with a lower heater cooling air passage formed around the lower heater to allow an air current to flow through while cooling said lower heater, and fourth air current forming means for forming the air current flowing in said lower heater cooling air passage, whereby the air current from said lower heater cooling air passage is discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       19. The built-in microwave oven according to  claim 18 , wherein said lower heater cooling air passage communicates with an end of a lower air passage defined between a lower partition panel and a bottom wall of said cavity. 
     
     
       20. The built-in microwave oven according to  claim 9 , further comprising a central guide provided within the external casing at a position before the exhaust grille for separately guiding the air from the inside passage and the air from the outside passage to opposite end portions of the exhaust grille. 
     
     
       21. The built-in microwave oven according to  claim 9 , further comprising a channel member used for forming an air duct and guiding an air current to flow through the air duct so as to prevent heat of said heating means from being transferred to said external casing. 
     
     
       22. A built-in microwave oven, comprising: 
       an external casing forming a profile of said microwave oven;  
       a cooking cavity set within the external casing and used for heating food seated therein;  
       a machine chamber provided within said external casing at a position around the cooking cavity, and encasing high-frequency electromagnetic wave generating means therein;  
       heating means for generating heat and radiating the heat into said cooking cavity;  
       a suction grille and an exhaust grille provided on a front wall of said external casing at predetermined upper and lower positions, respectively;  
       air current forming means for guiding inflow air from the suction grille to allow said air to pass within the external casing prior to discharging the air from the external casing to the atmosphere through the exhaust grille;  
       a first passage used for partially and directly guiding the inflow air from said suction grille to said exhaust grille;  
       a second passage used for partially guiding the inflow air from the suction grille to allow said air to pass by the heating means while cooling the heating means prior to reaching the exhaust grille; and  
       a third passage used for partially guiding the inflow air from the suction grille to allow said air to pass through the machine chamber prior to reaching the exhaust grille,  
       whereby said first, second and third passages are joined together at a position before the exhaust grille.  
     
     
       23. The built-in microwave oven according to  claim 22 , further comprising a partition wall installed at a junction of the bottom wall of said cavity and the bottom wall of said machine chamber and used for preventing exhaust air from being undesirably introduced into said machine chamber prior to being discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       24. The built-in microwave oven according to  claim 22 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between a top wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing;  
       wherein said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       25. The built-in microwave oven according to  claim 22 , wherein said heating means comprises an upper heater externally provided on a top wall of said cavity, and a lower heater externally provided on a bottom of said cavity, with a lower heater cooling air passage formed around the lower heater to allow an air current to flow through while cooling said lower heater, and fourth air current forming means for forming the air current flowing in said lower heater cooling air passage, whereby the air current from said lower heater cooling air passage is discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       26. The built-in microwave oven according to  claim 22 , further comprising a channel member used for forming an air duct and guiding an air current to flow through the air duct so as to prevent heat of said heating means from being transferred to said external casing. 
     
     
       27. A built-in microwave oven, comprising: 
       an external casing forming a profile of said microwave oven;  
       a cooking cavity set within the external casing and used for heating food seated therein;  
       a machine chamber provided within said external casing at a position around the cooking cavity, and encasing high-frequency electromagnetic wave generating means therein;  
       heating means for generating heat and radiating the heat into said cooking cavity;  
       a suction grille and an exhaust grille provided on a front wall of said external casing at predetermined upper and lower positions, respectively;  
       air current forming means for guiding inflow air from the suction grille to allow said air -to pass within the external casing prior to discharging the air from the external casing to the atmosphere through the exhaust grille;  
       a first passage used for partially guiding the inflow air from the suction grille to allow said air to pass by the heating means prior to reaching the exhaust grille; and  
       a second passage used for partially guiding the inflow air from the suction grille to allow said air to pass through the machine chamber prior to reaching the exhaust grille,  
       whereby said first and second passages are joined together at a position before the exhaust grille.  
     
     
       28. The built-in microwave oven according to  claim 27 , wherein said partition panel unit comprises: 
       an upper partition panel dividing a channel between atop wall of said cavity and a top wall of said external casing;  
       a side partition panel dividing a channel between a sidewall of said cavity and a sidewall of said external casing; and  
       a lower partition panel dividing a channel between a bottom wall of said cavity and a bottom wall of said external casing;  
       wherein said upper, side and lower partition panels continuously extend from each other, thus each dividing the channel between the cooking cavity and the external casing into one inside passage and one outside passage, and said lower partition panel is provided at a predetermined portion on the bottom wall of said cooking cavity for allowing the inside and outside passages formed by said lower partition panel to be joined together.  
     
     
       29. The built-in microwave oven according to  claim 27 , wherein said heating means comprises an upper heater externally provided on a top wall of said cavity, and a lower heater externally provided on a bottom of said cavity, with a lower heater cooling air passage formed around the lower heater to allow an air current to flow through while cooling said lower heater, and fourth air current forming means for forming the air current flowing in said lower heater cooling air passage, whereby the air current from said lower heater cooling air passage is discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       30. The built-in microwave oven according to  claim 27 , further comprising a partition wall installed at a junction of the bottom wall of said cavity and the bottom wall of said machine chamber and used for preventing exhaust air from being undesirably introduced into said machine chamber prior to being discharged from the external casing to the atmosphere through the exhaust grille. 
     
     
       31. The built-in microwave oven according to  claim 27 , further comprising a channel member used for forming an air duct and guiding an air current to flow through the air duct so as to prevent heat of said heating means from being transferred to said external casing.